Abstract
We consider the rheology of steady two-dimensional granular flows, in different geometries, using discrete element method–based simulations of soft spheres. The flow classification parameter , which defines the local flow type (ranging from pure rotation to simple shear to pure extension), varies spatially, to a significant extent, in the flows. We find that the material behaves as a generalized Newtonian fluid. The scaling proposed by Jop et al. [Nature (London) 441, 727 (2006)] is found to be valid in both two-dimensional and unidirectional flows, as observed in previous studies; however, the data for each flow geometry fall on a different curve. The results for the two-dimensional silo flow indicate that the viscosity does not depend directly on the flow type parameter, . We find that the scaling based on “granular fluidity” [Zhang and Kamrin, Phys. Rev. Lett. 118, 058001 (2017)] gives good collapse of the data to a single curve for all the geometries. The data for the variation of the solid faction with inertial number show a reasonable collapse for the different geometries.
- Received 1 November 2017
- Revised 15 February 2018
DOI:https://doi.org/10.1103/PhysRevFluids.3.062301
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